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Abstract:
In-situ UV-VIS spectroscopy in transmission and reflection mode as well as on-line GC and TPD MS were performed on pressed and powdered wafers made from industrial aluminas in different microreactor cells at 400 K.
These investigations were carried out on activated samples using a continuous gas flow of He containing either
H2S (1%) or SO2 (0.5%) or H2S (1%) with SO2 (0.5%) or 02 (0.5 and 5.0%). The adsorbed reactants lead to an absorption band at 290 nm (H2S and SO2). This absorption band could be attributed to chemisorbed species. Using a differential microreactor for transmission spectroscopy, a conversion of ca. 10% was measured in the
steady state and an attribution of the different visible absorption bands to S2-2 to S2-4 (H2S oxidation by 02)
and S2-3 to S2-x (modified Claus reaction, 2H2S+SO2=(3/x) Sx+3H2O) seems plausible. The species S2-8 may be responsible for the stationary conversion during the modified Claus reaction.
